Musical instrument



Nov. 11, 1941. L. HAMMOND 2,262,179

MUSICAL mswmmmm Original Filed July so, 1940 2 sheets-sheet 1 ax"ksflammon d Nov. 11, 1941. HAMMOND MUSICAL INSTRUMENT 2 Sheets-Sheet 2Original Filed July 30, 1940 Patented Nov. 11, 1941 MUSICAL INSTRUMENTLaurens Hammond, Chicago, Ill.

Original application July 30, 1940, Serial No. 348,414. Divided and thisapplication October 21, 1940, Serial No. 362,017

(Cl. 84l77) 7 Claims.

My invention relates generally to musical instruments, and moreparticularly to improvements in the construction of cases for electricalmusical instruments.

This application is a division of my co-pending application Serial No.348,414, filed July 30, 1940.

It is an object of my invention to provide an improved case for anelectrical musical instrument in which loud speakers are incorporated,and provision is made for improved acoustic output of the speakers.

A further object is to provide an improved case for an electricalmusical instrument in which the electrical parts are readily accessiblefor inspection and servicing.

A further object is to provide an improved case for electrical musicalinstruments which is of improved construction having good acousticalcharacteristics, in which the component parts are readily accessible,and which may be economically manufactured.

Other objects will appear from the following description, referencebeing had to the accompanying drawings in which:

Figure 1 is a perspective view of the instrument;

Figure 2 is a fragmentary sectional view of the instrument taken onvertical planes, one passing through the speaker, and the other behindthe control panel;

Figure 3 is a fragmentary right-side elevational view with the casecover as shown in raised position;

Figure 4 is a fragmentary side elevational view showing the generatorassembly in vertical position; and

Figures 5 and 6 are fragmentary details showing the electricalconnections between the generator assembly and the keyboard assembly.

As best shown in Figs. 1 and 2, the instrument comprises a caseconsisting of a main supporting frame l0 carried by four legs l2, thebottoms of the legs at each side being joined by rung bars I4. A soundreflecting board I6 is carried by the rungs H, the support I6 also beingconnected to a power supply enclosure l8 and serving as a support for anexpression pedal 28 and various sustaining pedals 22.

A key manual assembly 24 is mounted upon the main supporting frame III,while a control panel 26 is carried by a generator assembly designatedgenerally by the reference character 28. A case cover comprises a pairof side walls 30, 3|, a rear wall 32, and the top 34 which are rigidlysecured together and are hinged to the main supporting frame III by ahinge 36.

A music rack 38 is hinged to a front cross member 48 which is secured tothe side members and 3|, therebeing an opening 4| between the rear edgeof the music rack supporting member 46, and the forward edge of the top34. A top extension plank 42 is hinged to the forward edge of the top34, and has hinged thereto a front cover board 44. These parts 38, 42and 44 are so conformed that when the music rack 38 is swung forwardlyto a horizontal position, the boards 42 and 44 may likewise be swungforwardly so that the board 42 will form an extension of the top 34 andcover the music rack, while the front cover 44 will drop into a verticalposition in front of the manual 24, thus completely enclosing the spacein which the manual 24 and control panel 26 are located.

The instrument disclosed comprises a plurality of vacuum tubes 46constituting generators and control tubes, as disclosed in my priorPatent No. 2,126,682, these tubes 46 and other electrical elements ofthe circuit being designated generally the generator assembly 28. Asshown in Fig. 2, the tubes are supported upon a frame consisting ofangle irons 48and a sheet 50, the tubes being arranged in channelsextending from the front to the rear of the instrument, the channelsbeing formed by shielding enclosures consisting of vertical sheets 52 tothe upper edges of which are hinged horizontal cover sheets 54. Theforward ends of the channels are closed by sheets 56, while the rearwardends thereof are closed by sheets 58. Suitable partitions 66 areprovided to form electrostatic shields between adjacent groups of tubesin each of the channels.

The angle irons 48 have their ends secured to side planks 62 and 63which are secured to the main supporting frame III by studs 64, 65, thelower ends of which are threaded in suitable sockets formed in the sidesof the main frame III. A pair of similar angle irons 66, 6'! have theirhorizontal legs rigidly secured to the main frame l0, and have notches66 (Fig. 3) formed adjacent their rearward ends to receive theprojecting ends of lag screws 18 when the generator assembly is in itsnormal position, the lag screws being threaded into the side planks 62and 63. Each of the side planks 62, 63 has a lag screw 12 threadedtherein adjacent the rear end thereof. Handhole openings 14, 16 areprovided in each of the side planks 62, 63.

Attached to the rearmost angle 48 of the generator assembly is a strip18 of insulating material to which a plurality of soldering lugs 80 areattached. A similar strip 82 of insulating material is secured to atransverse board 84 which is rigid with the main supporting frame Hi,this strip 82 having a plurality of soldering lugs 88 riveted thereto.The lugs 86 are each provided with an eye portion 81 to receive the endof a coil spring 88, the other end of each of the coil springs beinganchored in a hooked portion 8| of one of the lugs 80. Conductors 98 aresoldered respectively to the lugs 88, and have their other ends securedto electrical elements of the generator system 28. Lugs 88 similarlyhave conductor 82 solder-ed thereto, which lead to electrical elementsforming parts of the keying circuits of the manual 24.

When it is desired to obtain access to the underside of the generatorassembly 28 the studs 64, 85 are removed, and by grasping first theright-side plank 82, the assembly is raised sufliciently to remove thelag screw 18 from its slot 68, and the assembly is swung forwardlyslightly to bring the lag screw to rest in a recess 84 formed in theupper edge of the angle 88. The other side plank B3 is then similarlyraised and shifted to bring its lag screw into a corresponding recess 84in its angle 81. Thus, when slightly elevated, the generator assemblymay be slid forwardly to the position in which it is shown in dottedlines in Fig. 3, the angles 86 and 81 forming guides, while the lagscrews 18 rest upon the upper edges of these angle irons.

The forward sliding movement of the generator assembly is limited by theengagement of lag screws 12 with the rearward ends of the angle irons86, 81. When the generator assembly is in this position the rearwardlower corners of the side planks B2 and 53 will be in alignment with therearward edges of notches 86 formed in the main supporting frame, sothat the generator assembly may have its forward end raised and swung toa vertical position. The engagement of the lower rear corners of theside planks 62 and 63 in the notches 85 prevents the generator assemblyfrom sliding rearwardly as its forward end is being swung upwardly. Thegenerator assembly is swung upwardly to the posi-, tion in which it isshown in Fig. 4, in which position it is stable, and the underside ofthe generator assembly is available for inspection and servicing.

It will be noted, by reference particularly to Figs. 3 and 4, that asthe generator assembly is moved from its normal position to its verticalposition, the springs 88 are stretched and swung about, but neverthelessmaintain the electrical connection between their respective lugs 80 and88, so that even when the generator assembly is in its verticalposition, all of the electrical connections are maintained and theinstrument is in operative condition. Thus, testing and servicing of theinstrument is greatly facilitated.

To return to the generator assembly 28 to its normal position, it isswung forwardly and downwardly from the position shown in Fig. 4 to thedotted line position of Fig. 3, in which position it is arrested andlocated by the engagement of its lag screws 18 with the upper edges ofthe angle irons 66 and B1. The generator assembly may then be pushedrearwardly until the lag screws 18 drop into the recesses 94, whereuponthe lag screws 18 may be dropped into their eating notches 88. Thislatter operation may be performed first at one side and then at theother.

Although the generator assembly may have an aggregate weight in excessof one hundred pounds, the mounting, as described above, makes itpossible for one person to swing it quite easily to the position shownin Fig. 4, and to return it to normal position. Such movement of thegenerator assembly is possible without disturbing any of the electricalconnections between the generator assembly and the manual assembly,because of the provision of the resilient spring I connections 88between the two assemblies.

When it is desired to remove the generator assembly from the instrument,the springs 88 may be unhooked from their lugs 88, thus very quickly andeasily severing the electrical connections between the generatorassembly and the manual assembly. The operation of unhooking the springsfrom their lugs and rehooking them when the generator is to be replacedis very simple, and avoids the necessity of breaking and remakingsoldered connections, which would otherwise be necessary. It will beunderstood that the springs 88 are at all times under sufilcient tensionto maintain good electrical contact with their supporting lugs.

In the instrument disclosed there are provided two loud speakers 96, 81which are mounted upon sloping panels 98, the angle of the panel-s 88being such that the acoustic beam of the loud speaker will strike theboard [6, and the latter will thus reflect a large proportion of thesound energy upwardly and outwardly into the room. If the reflectingboard I8 were not provided and the instrument were placed upon a rug 0:carpet, the absorption of sound by the latter would be so great,especially of the higher frequency sounds, that the music would beimpaired.

The backs of the speakers are in free communication with the spacewithin the cover of the case, and an exit for the sound waves generatedby the back of the speaker diaphragm is provided by the opening ll. Thegenerator assembly 28 does not completely fill the space within thecover, and there are numerous paths for the travel of sound through andaround this assembly. This forms an excellent acoustic arrangement,since a player sitting at the manual will hear the sound produced as ifit were emanating from the case itself, in the same manner that thesound from grand piano strings is in part transmitted directly from thestrings and in part transmitted through the sounding board. The caseitself thus provides a relatively large baille for the speakers, andalso provides an acoustic reflecting surface to assure good productionof the music even though the acoustic properties of the room in which itis being played are not as favorable as might be desired.

While I have shown and described a particular embodiment of myinvention, it will be apparent to those skilled in the art that numerousvariations and modifications may be made without departing from theunderlying principles of the invention. I therefore desire, by thefollowing claims, to include within the scope of my invention, all suchvariations and modifications by which substantially the results of myinvention may be obtained through the use of substantially the same orsimilar means.

I claim:

1. In an electrical musical instrument having a manual and in which theacoustic output is produced by loud speakers, a case providing anenclosure for some of the electrical portions of the instrument, saidcase having an opening above the manual and having a pair of openings inits bottom, a pair of loud speakers having their diaphragms respectivelyclosing said pair of openings in the bottom of said case, said speakershaving the axes of their diaphragms directed downwardly and divergingly,and a part of said case forming relatively large hard acousticreflecting surfaces intersecting the axes of said speaker diaphragmsrespectively at an angle thereto.

2. In an electrical musical instrument having a manual and in which thacoustic output is produced by loud speakers, a case providing anenclosure for some of the electrical portions of the instrument, saidcase having an opening above the manual and having a pair of openings inits bottom, and a pair of loud speakers having their diaphragmsrespectively closing said pair of openings and directed outwardly fromthe bottom of said case, the backs of said speaker diaphragms beingacoustically in communication with said opening above the manual.

3. In an electrical musical instrument having a manual and in which theacoustic output is produced by a loud speaker, a case providing anenclosure for some of the electrical portions of the instrument, saidelectrical portions filling a part only of the space within said case,said case having an opening above the manual and having an opening nearits bottom, and a loud speaker having its diaphragm closing said openingnear the bottom of said case and directed outwardly from said case, saidspeaker having the back of its diaphragm open to the space within saidcase, 2

whereby sound radiated from. the back of the speaker diaphragm will betransmitted through the space within the case around said electricalportions of the instrument and through said opening above the manual.

4. In a case for an electrical musical instrument having a manual forcontrolling the acoustic output of the instrument, an electroacoustictranslating means provided with a sound generator having directionalcharacteristics, the axis of the acoustic output of said sound generatorbeing directed downwardly and outwardly with respect to the centralportion of the case, and means forming a part of said case and providingan acoustic reflecting surface intersecting the axis of the acousticoutput of said generator at an angle thereto, whereby the sound producedwill be reflected outwardly and upwardly from said surface.

5. In an electrical musical instrument having a manual and in which theacoustic output is produced by loud speakers, a case providing anenclosure for some of the electrical portions of the instrument, saidcase having an opening above the manual and having a pair of openings inits bottom, a pair of loud speakers having their diaphragms closing saidopenings in the bottom of said case, said speakers having the axes oftheir diaphragms directed downwardly, and a part of said case formingrelatively large hard acoustic reflecting surfaces intersecting the axesof said speaker diaphragms respectively at an angle thereto to reflectthe sound produced by said speaker diaphragms upwardly and outwardlyfrom said case.

6. In an electrical musical instrument having a manual and in which theacoustic output is produced by loud speakers, a case providing anenclosure for some of the electrical portions of the instrument, saidcase having an opening above the manual and having a pair of openings inits bottom, a pair of loud speakers having their diaphragms respectivelyclosing said pair of openings and directed downwardly from the bottom ofsaid case, th backs of said speaker diaphragms being acoustically incommunication with said opening above the manual, and sound reflectingmeans forming parts of said case and positioned to reflect the soundproduced by the front surfaces of said speaker diaphragm upwardly andoutwardly.

7. In an electrical musical instrument having a manual and in which theacoustic output is produced by a loud speaker, a case providing anenclosure for som of the electrical portions of the instrument, saidelectrical portions filling a part only of the space within said case,said case having an opening adjacent the manual and having an openingnear its bottom, a loud speaker having its diaphragm closing saidopening near the bottom of said case and facing downwardly, said speakerhaving the back of its diaphragm open to the space within said case,whereby sound radiated from the back of the speaker diaphragm will betransmitted through the space within the case around said electricalportions of the instrument and through said opening adJacent saidmanual, and means forming part of said case providing a relatively hardsound reflecting surface to reflect upwardly the sound emitted from thefront of said speaker diaphragm.

LAURENS HAMMOND.

